General Biology 5 Q1

Cell Cycle

The series of events a cell goes through to grow and divide: Interphase, Mitosis, and Cytokinesis

Interphase

The growth and preparation phase composed of G1 (growth), S (DNA synthesis), and G2 (preparation for mitosis)

G1 Phase

The first and longest part of interphase where the cell grows, carries out normal functions, and duplicates organelles

S Phase

The part of interphase when DNA is replicated so each daughter cell will receive a full genome

G2 Phase

The final interphase stage when the cell finishes growth and assembles materials needed for mitosis

Mitosis

The division of the nucleus into two genetically identical nuclei, consisting of Prophase, Metaphase, Anaphase, and Telophase (PMAT)

Prophase

Chromosomes condense, the nuclear envelope breaks down, and spindle fibers form

Metaphase

Chromosomes align at the cell equator and spindle fibers attach to centromeres

Anaphase

Sister chromatids separate and are pulled to opposite poles of the cell

Telophase

Chromosomes decondense, nuclear envelopes reform, and two nuclei are established

Cytokinesis

The division of the cytoplasm after mitosis that produces two daughter cells (cleavage furrow in animals

cell plate in plants)

Chromatin vs Chromosome

Chromatin is the relaxed form of DNA in nondividing cells

chromosomes are condensed, visible DNA structures during division

Chromatid and Centromere

Each chromosome copy consists of two sister chromatids joined at the centromere

Chromosome Number

The characteristic number of chromosomes in an organism (e.g., human = 46)

Checkpoints

Regulatory control points (G1/S, G2/M, and spindle checkpoint) that ensure DNA integrity and proper progression through the cycle

DNA Replication

The accurate copying of genetic material during S phase so daughter cells inherit identical genomes

Cell Division Control

DNA and regulatory proteins normally control division

when control is lost, cells may divide uncontrollably

Tumor

A mass of abnormal cells caused by uncontrolled cell division

Benign Tumor

Noninvasive tumor that does not spread to other tissues

Malignant Tumor

Cancerous tumor that can invade surrounding tissue and spread to other body parts (metastasize)

Metastasis

The process by which cancer cells break away and establish new tumors in other locations

Cancer

Not a single disease but many diseases where cells lose normal division control, often due to DNA damage or mutation